1. Field of the Invention
The invention is based on an electric motor and fan wheel combination as defined hereinafter.
2. Description of Related Prior Art
U.S. Pat. No. 3,264,506 discloses an electric motor and fan wheel combination having a housing, having an armature and a collector in the housing, two slide bearings in the housing, an armature shaft supported by means of the slide bearings and carrying the armature and the collector. The armature has an armature shaft end protruding out of the housing, and a fan wheel that has a hub which is secured to the armature shaft end. Both slide bearings have slide bearing bushes, disposed in such a way that they can execute tilting motions, with face-end bearing faces, so that the slide bearing bushes together with the armature shaft form two radial bearings, and that face-end bearing faces of the two slide bearing bushes oriented toward the armature and the collector, together with annular disks built in between them and the armature and the collector and surrounding the armature shaft, additionally form two axial bearings. These axial bearings limit the displaceability of the armature shaft in the axial direction. To enable setting the axial play to a magnitude of substantially 0.125 mm, for example, the housing of the electric motor comprises two substantially cup-shaped housing parts, one of which can be inserted in telescoping fashion into the other to reduce the originally excessive longitudinal armature play to the desired value, which is associated with less noise in operation of the electric motor. Once the axial play has been set to the intended value, weld seams are made on the two housing parts, so that the mutual orientation of the housing parts and thus the set axial play are preserved. In this state, the hub of the fan wheel has an axial spacing from an adjacent bearing bush. The annular disks are made from sheet steel, for instance, and are embodied on their circumference in the manner of the rim of a plate, so that in addition to furnishing axial bearing slide faces, they also act as spinner rings for oil, with which the porous slide bearing shells are saturated.
U.S. Pat. No. 3,624,434 discloses an electric motor that is intended for instance for combination with the fan wheel of the aforementioned U.S. Pat. No. 3,264,506. This electric motor has a housing, an armature, a collector, and two slide bearings in the housing. An armature shaft is supported by means of the slide bearings and carries both the armature and the collector and has an armature shaft end protruding out of the housing, on which end a hub of the fan wheel is secured. Both slide bearings have slide bearing bushes with face-end bearing faces, the slide bearings receiving the armature shaft, and both face-end bearing faces of one of the slide bearing bushes, together with an annular disk disposed between the collector and this slide bearing bush about the armature shaft, and with an axial bearing, press-fitted on the far side of the annular disk on a free end of the armature shaft that is inserted through the slide bearing, forms a bidirectional axial bearing for the armature shaft. As a result, the slide bearing, formed of the annular disk, the axial stop ring and the sliding bush located between them, forms what in German is called a fixed bearing, while conversely the other slide bearing, which is adjoined by the armature shaft end intended for the fan wheel, is known in German as a loose bearing. What this means is that this loose bearing generates only radial bearing forces and does not present any resistance to displacement of the armature shaft, or in other words loosely receives the armature shaft in the is axial direction. The annular disk, as a component of the axial bearing, is made from sheet metal and has a rim similar to that of a plate, so that the annular disk, in addition to furnish an axial bearing face, also acts as an oil spinner ring to prevent oil from migrating out of the porous slide bearing bush to the collector.
The electric motor and fan wheel combination according to the invention is economical, because a hub, which is required anyway, of the fan wheel, makes the task of the axial stop ring of the prior art for forming an axial bearing unnecessary. This accordingly saves on installation space in the housing of the electrical motor in the prior art that is intended for the axial stop ring.
By means of the characteristics recited herein advantageous embodiments of the electric motor and fan wheel combination defined are possible.
The definitive characteristics set forth herein have an advantage of an elastic and thus noise-reducing limitation of the displaceability of the armature shaft relative to the housing of the electric motor. Accordingly, the hub of the fan wheel is prevented from striking the slide bearing bush hard and thus the projection of irritating clacking noises through the housing of the electric motor of the fan wheel is averted.
Other definitive characteristics disclose an exemplary embodiment that can be produced economically.
Yet other definitive characteristics set forth can be employed alternatively and offer the advantage of easier mounting of the hub of the fan wheel on the armature shaft end, because a press fit can be embodied less rigidly. For the exemplary embodiments set forth, a sliding fit suffices for disposing the respective hub on the armature shaft end.
The method defined by the characteristics the advantage that to set the axial play, there is no need to introduce a feeler gauge between the slide bearing bush and the hub of the fan wheel. As a result, beginning at the hub, a carrier body that carries a number of fan blades can be embodied in shell-like fashion, surrounding the electric motor over a portion of its length.
The method having the definitive characteristics set forth herein are employed to produce the electric motor and fan wheel combination.